Runtime error when importing `sharp` (pnpm / Vite+Nitro / TSS)

[TmLev]

Title

Workflow runtime fails to load sharp while equivalent regular server path works (pnpm / Vite + Nitro / TanStack Start)

Repro

https://tss-workflow-sharp-bug.vercel.app/

Source code: https://github.com/TmLev/tss-workflow-sharp-bug

Summary

In the same app, sharp works in a regular server function but fails in a Workflow step at runtime.

• workflow path: start(sharpWorkflow) ("use workflow" + "use step")
• regular path: same resize logic, no workflow directives

Expected

Both paths should return a successful resize result.

Actual

Regular path works, workflow path crashes indefinitely until stopped manually with:

2026-02-11 12:32:22.967 [error] Error: Could not load the "sharp" module using the linux-arm64 runtime
Possible solutions:
- Ensure optional dependencies can be installed:
    npm install --include=optional sharp
- Ensure your package manager supports multi-platform installation:
    See https://sharp.pixelplumbing.com/install#cross-platform
- Add platform-specific dependencies:
    npm install --os=linux --cpu=arm64 sharp
- Consult the installation documentation:
    See https://sharp.pixelplumbing.com/install
    at node_modules/.pnpm/sharp@0.34.5/node_modules/sharp/lib/sharp.js (/var/task/index.js:2140:13)
    at __require (/var/task/index.js:13:50)
    at node_modules/.pnpm/sharp@0.34.5/node_modules/sharp/lib/constructor.js (/var/task/index.js:2152:5)
    at __require (/var/task/index.js:13:50)
    at node_modules/.pnpm/sharp@0.34.5/node_modules/sharp/lib/index.js (/var/task/index.js:7876:17)
    at __require (/var/task/index.js:13:50)
    at Object.<anonymous> (/var/task/index.js:30348:28)
    at Module.<anonymous> (/opt/rust/bytecode.js:2:1435)
    at A.d._compile (/opt/rust/bytecode.js:2:3186)
    at Object..js (node:internal/modules/cjs/loader:1839:10)
Node.js process exited with exit status: 1. The logs above can help with debugging the issue.

(Full logs are in the repo README)

Notes

• I understand TanStack Start is not officially supported yet, but there is an open PR/discussion acknowledging it is a wrapper around Vite+Nitro (which are supported): feat: add tanstack support #877
• In this repro, Vercel build is linux-x64 and Workflow runtime is linux-arm64; despite that, regular sharp still works.
• In my production project (Pro plan), builds are linux-x64 (GitHub Actions) and Workflow runtime is also linux-x64 (matching arch), and I still hit the workflow-specific failure pattern.

[kierianlee]

Can confirm, happens to me as well

[TmLev]

@pranaygp is there any context I can provide to make this easier to debug and address?

[kevindente]

We're hitting this as well. Any word on a workaround?

[JClackett]

ah was hoping this wasn't the case, im also experiencing this too

[TmLev]

I asked GPT-5.5-xhigh to ruminate on this and it found this workaround for "user space":

diff --git a/vite.config.ts b/vite.config.ts
index 7260c1b..f60f8bb 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -1,16 +1,56 @@
+import { access, cp } from "node:fs/promises";
+import { join } from "node:path";
+ 
+function copyTracedNodeModulesToWorkflowFunctions() {
+  return {
+    name: "copy-traced-node-modules-to-workflow-functions",
+    apply: "build" as const,
+    async closeBundle() {
+      const functionsDir = fileURLToPath(
+        new URL("./.vercel/output/functions", import.meta.url),
+      );
+      const tracedNodeModules = join(
+        functionsDir,
+        "__server.func",
+        "node_modules",
+      );
+
+      try {
+        await access(tracedNodeModules);
+      } catch {
+        return;
+      }
+
+      const workflowFunctionDirs = [
+        ".well-known/workflow/v1/step.func",
+        ".well-known/workflow/v1/flow.func",
+        ".well-known/workflow/v1/webhook/[token].func",
+      ];
+
+      await Promise.all(
+        workflowFunctionDirs.map((functionDir) =>
+          cp(tracedNodeModules, join(functionsDir, functionDir, "node_modules"), {
+            recursive: true,
+            force: true,
+          }),
+        ),
+      );
+    },
+  };
+}
+
@@ -19,7 +59,7 @@ const config = defineConfig({
     devtools(),
     nitro({ preset: "vercel" }),
     workflow({ runtime: "nodejs24.x" }),
+    copyTracedNodeModulesToWorkflowFunctions(),
     tailwindcss(),
     tanstackStart(),
     viteReact(),

And it also made this PR to fix the underlying issue: #1856